Interesting article and though both companies have a differing market view, this one sentence summed it up for me.
ANd it's been 5 1/2 years, not 3~4. Canon has done little to improve IQ since the 5DII and the 7D. Little things here and there and a big focus on video, but they are leaving the still shooters out of the picture.
No, it hasn't been that long for the 18MP crop sensor. FF maybe, but the 18Mpx crop version is only a couple of years old. And the 1DX, 5D3 and 6D have hugely better ISO capability than the previous generation.